Poland's prime minister Donald Tusk has warned that Russia is likely to escalate its campaign of sabotage and disruption against Europe before Christmas.
Lithuania is ending its decades-old ban on hosting nuclear weapons and running mass evacuation drills to prepare for a possible Russian attack.
NATO fighter jets shot down a drone that flew into airspace over Lithuania, a NATO member country in the Baltic region.
Researchers, an Italian outlet and Lithuania documented a summer of drone incursions, weapons caches and border crossings on EU soil, plus online attacks on NATO countries run like a competitive game among pro-Russian hackers.
US intelligence believes Russian President Vladimir Putin might try a small military attack on a NATO country to test the alliance's response, according to the Wall Street Journal.